rdsn

const shares = ['1.5', '3', '6', '1.5'];

const transformToPercentShares = (rationalShares) => {
  if (!rationalShares) {
    throw new Error('Argument is missing');  
  } else if (!Array.isArray(rationalShares)) {
    throw new TypeError('Argument should be an array');
  } else if (!rationalShares.length) {
    throw new Error('Argument must contain at least one value');
  }

rdsn

ES6 JavaScript Compose Function

Definition

const compose = (...fns) =>
  fns.reduceRight((prevFn, nextFn) =>
    (...args) => nextFn(prevFn(...args)),
    value => value
 );